Method and system for power load management

ABSTRACT

A method for power load management is provided in the present invention, wherein two different standard values are determined to be a basis for regulating power consumption. When power consumption exceeds a first standard value, a monitoring procedure is started to monitor consumption status. If the power consumption exceeds a second standard value, an unloading procedure is processed to reduce the power consumption of electrical devices under operation. In another embodiment, the present invention also provides a system for power load management comprising a control unit coupled to at least one electrical device and a power meter. By means of real-time recording of power consumption in the power meter, the control unit is capable of determining the power consumption status and determining whether it is necessary to unload or reload the at least one electrical device.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a method and a system forpower load management and, more particularly, to a method and a systemfor power load management capable of controlling the timing forunloading or reloading an electrical device according to powerconsumption thereof.

2. Description of the Prior Art

Due to the raise in oil and coal prices in recent years, the cost ofgenerating power has significantly increased. Moreover, the green houseeffect worsens the global warming that ecologically affects the earth.Therefore, various measures for energy conservation have been takenthroughout the world.

The air conditioner plays an important role in the summer for peopleliving in the subtropical countries. Such an electric device is a powereater even though it brings forth comfort in the room during the summer.Statistically, the power consumption of the air conditioning systemsoccupies 30˜4% of the peak load in the summer. Therefore, it has been animportant issue to provide comfort in the living/working places withreduced power consumption.

In the prior art, such as Taiwan Pat. Pub. No. 200742819, there isdisclosed a power saving device disposed in and electrically coupled toa temperature adjustment device. The power saving device comprises atleast a temperature sensor, a processing unit and a switching unit. Thetemperature sensor issues a sensed signal of temperature to theprocessing unit, which generates a switching signal according to sensedsignal. The switching unit switches a compressor to an operation stateor a static state according to switching signal.

Moreover, Taiwan Pat. No. 175182 discloses a power control device for acentralized air conditioning system, using the outdoor temperature, theindoor temperature, the temperature of water flowing from/into thecooling tower and the pre-set temperature as control parameters tocontrol the compressor, the cooling pump and the fan in the coolingtower of the air conditioning system according to a software program toprovide comfort with reduced power consumption.

Moreover, U.S. Pat. No. 6,493,643 discloses a power control methodcapable of controlling the operation of electrical devices within a zoneaccording to the detected total power consumption. This patent is usefulin power saving management for home-use electrical devices. Moreparticularly, the method uses a controller acquires real-time powerconsumption information of the electrical devices from the AC utilityvia internal communication devices to compare with a maximum valuedetermined by a logical controller, time-of-use electricity tariff andthe operation state of the electrical devices to generate a signal tothe home-use plugs to control the power consumption. In this patent, thepower consumption is compared with a standard value, which causesshed-load or reload of the system due to poor control accuracy.

SUMMARY OF THE INVENTION

It is one object of the present invention to provide a method for powerload management, in which two standard values are determined todetermine the timing for unloading/reloading of electrical devicesaccording to a power consumption status and the relation between the twostandard values so that the power consumption status is controlled tothus reduce power consumption.

It is another object of the present invention to provide a method and asystem for power load management, in which the moving average for powerconsumption status in different time periods is compared to the twostandard values so as to assure the control accuracy and the efficiencyof the electrical devices.

It is another object of the present invention to provide a method and asystem for power load management, in which a reload mechanism is furtherdetermined to reload the unloaded electrical device when the powerconsumption status or unload time is conformed to some conditions.

In one embodiment, the present invention provides a method for powerload management, comprising steps of: determining a first standard valueand a second standard value; determining a first monitoring value and asecond monitoring value according to a power consumption status;determining whether the second monitoring value is larger than thesecond standard value when the first monitoring value exceeds the firststandard value; and starting an unloading procedure if the secondmonitoring value is lamer than the second standard value.

In another embodiment, the present invention further provides a systemfor power load management, comprising: a power meter, coupled to a powersource to record a power consumption status; a control unit,electrically coupled to the power meter to issue an unloading signal ora reloading signal according to the power consumption status; and atleast an electrical device, coupled the control unit to receive theunloading signal or the reloading signal to be unloaded or reloaded.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, spirits and advantages of the preferred embodiments of thepresent invention will be readily understood by the accompanyingdrawings and detailed descriptions, wherein:

FIG. 1 is a flowchart of a method for power load management according tothe present invention;

FIG. 2 is a schematic diagram of a system for power load managementaccording to the present invention;

FIG. 3A and FIG. 3B show a flowchart of an unloading procedure accordingto the present invention;

FIG. 4 is a graph showing a power consumption curve, a first monitoringvalue curve, a second monitoring value curve and the relation curve of afirst standard value and a second standard value;

FIG. 5 is a flowchart of a reloading procedure according to the presentinvention; and

FIG. 6 is a schematic diagram of a logic control module according to thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention can be exemplified by the preferred embodiments asdescribed hereinafter.

Please refer to FIG. 1, which is a flowchart of a method for power loadmanagement according to the present invention. The method 1 for powerload management of the present invention is used in an electrical systemsuch as an air-conditioning system in a building or a large zone.However, the present invention is not limited thereto. In the presentinvention, the timing for unload/reload is controlled so as to providereliable electricity and meet the subscribers' requirement with reducedpower consumption. In FIG. 2, the method 1 comprises steps as described.First, in Step 10, a first standard value and a second standard valueare determined, in the present embodiment, the first standard value andthe second standard value represent the consumed power (in kilowatt).The first standard value is smaller than the second standard value. Thefirst standard value is determined by multiplying the second standardvalue with 90˜98%. However, the present invention is not limitedthereto. The second standard value is determined according to thecontract capacity approved by the power providing company. However, thepresent invention is not limited thereto. The contract capacity is anupper limit of supplied power for each subscriber by power providingcompany. If this upper limit is exceeded, the subscriber will be finedby the power providing company. The power providing company calculatesthe upper limit based on the average consumed power per 15 minutes to becompared with the contract capacity. If the maximum average consumedpower per 15 minutes exceeds the contract capacity, the subscriber hasbroken the contract.

Then, in Step 11, a first monitoring value and a second monitoring valueare determined according to a power consumption status. The powerconsumption status is determined by a power meter disposed between theelectrical system and the power providing company to indicate theconsumed power by the electrical system. According to the powerconsumption status, the first monitoring value and the second monitoringvalue are determined. In the present embodiment, the first monitoringvalue and the second monitoring value indicate the continuous movingaverages of the power consumption status. More particularly, the firstmonitoring value is the moving average per 12 minutes, while the secondmonitoring value is the moving average per 2 minutes. The period of thetime for determining the average is determined according to practicaluses and is not limited to the present embodiment. For example, in thepresent embodiment, since the power providing company calculates theexceeded power consumption according to the average consumed power per15 minutes to be compared with the contract capacity, in the presentembodiment, a first monitoring value is determined based on a period oftime of 2 minutes, while a second monitoring value is determined basedon a period of time of 2 minutes, resulting in a total of 14 minutes,which is shorter than the 15 minutes as a basis used by the powerproviding company, to achieve more precise control.

Then, in Step 12, whether the second monitoring value is larger than thesecond standard value when the first monitoring value exceeds the firststandard value is determined. In Step 12, a two-stage monitoringprocedure using the first standard value and the second standard valueis used. If the first monitoring value exceeds the first standard value,the relation between the second monitoring value and the second standardvalue is determined. Since the first monitoring value is the movingaverage per 12 minutes, the slope of the first monitoring value curve issmaller, as shown in FIG. 4, to avoid mis-determination. If the movingaverage per 12 minutes exceeds the first standard value, a powerconsumption peak is going to appear. Therefore, a second monitoringvalue (i.e., the moving average per 2 minutes) is used to intensivelymonitor the power consumption status. If the second monitoring value islarger than the second standard value, Step 13 is performed to start anunloading procedure.

Please refer to FIG. 2, which is a schematic diagram of a system forpower load management according to the present invention. The system 2comprises a power meter 20, a control unit 21 and at least an electricaldevice 22. The power meter 20 is coupled to a power source 90. The powermeter 20 is capable of recording real-time power consumption status perunit time. In the present embodiment, the power source 90 is asubstation for providing electricity. The control unit 21 iscommunicatively coupled to the power meter 20. The control unit 21electrically is coupled to the power meter 20 to issue an unloadingsignal or a reloading signal according to the power consumption statusrecorded in the power meter 20. Communicatively coupling is achieved viaa wired network or a wireless network using TCP/IP protocol forinformation transmission. The control unit 21 is a device witharithmetic ability such as a programmable logic controller (PLC) controlunit a computer or a workstation. In the present embodiment, tostabilize the system, the control unit 21 is a PLC control unit.

The electrical device 22 is coupled to the control unit 21 to receivethe unloading signal or the reloading signal to be unloaded or reloaded.In the present embodiment, the electrical device 22 is exemplified by,but not limited to, an air-conditioning device, which can be installedin a building, a community or a public place. Moreover, the control unit21 is coupled to an information display unit 24 as a user's interfacesuch as a workstation or a server, whereon software is installed tomonitor the operation status, power consumption status and relatedsettings of the system in FIG. 2. Certainly, all the information istransmitted to the control unit 21 as a basis for operation.

In FIG. 2, the power meter 20 is capable of recording the total consumedpower of the electrical devices such as air conditioners installed inthe monitored region including buildings, communities or public places.Then, the control unit 20 is capable of determining whether theelectrical device is to be unloaded or reloaded according to thereal-time recorded power consumption and the flowchart in FIG. 1.

Please refer to FIG. 3A and FIG. 3B for a flowchart of an unloadingprocedure according to the present invention. The system in FIG. 2 isexemplified to describe the flowchart of the method 3 in FIG. 3A andFIG. 3B. First, in Step 30, an unloading order is determined for all theelectrical devices. In this step, an electrical device that is not to beunloaded for the time being is selected according to practical use.Since the method of the present invention is capable of monitoring thepower consumption of electrical devices in a large area, an unloadingorder is required to be pre-determined as a basis for the unloadingprocedure because the number of electrical devices may be to large insuch a large area. Certainly, the present invention is not limited tothe present embodiment. In Step 31, a contract value, a first standardvalue, a second standard value and related parameters are provided.Then, in Step 32, the status of the system is confirmed. In the presentstep, Step 321 to Step 324 describe that the electrical devices 22 andthe control unit 21 operate in a communication state, starting or offstate, automatic mode or local mode. The automatic mode indicates thatthe electrical device 22 receives the unloading or reloading commandfrom the control unit 21, while the local mode indicates that theelectrical device 22 is no longer controlled by the control unit 21 tostop receiving any unloading or reloading command. Usually, when specialevents happen, it is required to stop unloading the electrical devicefor the time being.

Then in Step 33, referring to FIG. 4, the moving average per 12 minutesof the power consumption status obtained according to the powerconsumption (KW) per unit time recorded by the power meter 20 as a firstmonitoring value (12 mAVG) is compared to the first standard value(POD). If the first monitoring value (12 mAVG) is smaller than or equalto the first standard value (POD) at Point 91 in FIG. 4, the powerconsumption still has not exceeded the contract value and thus the alarmmodule 23 is off. When the first monitoring value (12 mAVG) is largerthan the first standard value (POD) at Point 92 in FIG. 4, the powerconsumption is likely to exceed the contract value and thus the alarmmodule 23 is turned on to inform the monitoring staff. As the alarmmodule 23 is turned on, Step 34 is performed to determine whether theelectrical device is to be unloaded. In the present step, instead ofcomparing the first monitoring value and the first standard value, asecond monitoring value (2 mAVG) (i.e., the moving average per 2 minutesof the power consumption status) and a second standard value (UDM) arecompared. If the second monitoring value (2 mAVG) is smaller than thesecond standard value (UDM) at Point 93 in FIG. 4, the current powerconsumption has not exceeded the contract value and thus the unloadingprocedure is not performed. On the contrary, if the second monitoringvalue (2 mAVG) is larger than the second standard value (UDM) at Point94 in FIG. 4, the power consumption is likely to exceed the contractvalue and thus a first unloading procedure is performed.

The unloading order of electrical devices in the first unloadingprocedure is according to Step 30. In the first unloading procedure, theloading capability of the main engine is reduced by a specificpercentage, for example, 20% in the present embodiment. The percentageof loading capability reduced is determined according to practical usesand is not limited to 20% as in the present embodiment. Therefore, afterthe first unloading procedure, the maximum loading capability is 80%left. Repeating Step 34, if the second monitoring value (2 mAVG) of thepower consumption is larger than the second standard value (UDM) afterthe electrical device is unloaded, a second electrical device is to beunloaded according to the unloading order. The relation between thesecond monitoring value and the second standard value is repeatedlymonitored until all the electrical devices 22 have been unloaded. In thepresent embodiment, it takes 2 minutes to determine whether anyelectrical device is to be unloaded. However, the present invention isnot limited to 2 minutes as in the present embodiment.

In Step 35, after all the electrical devices 22 have been unloaded, Step36 is performed to start a second unloading procedure if the secondmonitoring value (2 mAVG) is still larger than the second standard value(UDM). The unloading order of electrical devices in the second unloadingprocedure is according to Step 30. The second unloading procedure issimilar to that in Step 33 except that the loading capability of theelectrical device is reduced by 20% more in the second unloadingprocedure. Therefore, after the first and second unloading procedures,the maximum loading capability is 60% left. The number of unloadingprocedures and the reduction percentage are determined according topractical uses and the present invention is not limited thereto.

Please refer to FIG. 2 and FIG. 5, wherein FIG. 5 is a flowchart of areloading procedure according to the present invention. In the presentembodiment, the timing for the unloaded electrical devices to bereloaded is determined. When there is an unloaded electrical device 22,the control unit 21 monitors the unloaded time of the unloadedelectrical device. The unloaded time is monitored in Step 40 todetermine whether it has reached a pre-determined value, for example, 30minutes in the present embodiment. Moreover, each of the electricaldevices is provided with an optimal reloaded time according to itstemperature condition to achieve the best result. Step 41 is performedwhen the reloaded time comes to determine whether a reloading procedureis to be performed according to the comparison of the second monitoringvalue (the average value per 2 minutes) and the second standard value,if the second monitoring value (2 mAVG) is smaller than the secondstandard value (UDM), the power consumption is reduced. Meanwhile, Step42 is performed to determine whether the reloaded electrical device isthe last one. If not, Step 43 is performed to start a first reloadingprocedure to increase the maximum loading from 60% to 80%. On thecontrary, if the reloaded electrical device is the last one, a secondreloading procedure is started in Step 44 because the first reloadingprocedure has been performed on all the devices, resulting in anincrease of maximum loading from 80% to 100%.

Returning to Step 43, after the first electrical device 22 is reloaded,there is a waiting time, for example, 3 minutes in the presentembodiment. The second monitoring value and the second standard valueare compared to determine whether a next electrical device is to bereloaded. In Step 41, if the second monitoring value (2 mAVG) is largerthan the second standard value (UDM), the power consumption of thesystem is high and thus the device is not to be reloaded.

Returning to FIG. 2, the electrical device 22 further comprises a mainengine 220 and a logic control module 221. The main engine 220, in thepresent embodiment, is exemplified by, but not limited to, an airconditioner. The logic control module 221 is capable of receiving theunloading signal or the reloading signal to issue an operation signal tothe main engine 220. The logic control module 221 further comprises anunloading relay module 222 and a logic control unit 223. The unloadingrelay module 222 is electrically coupled to the main engine 220. Theunloading relay module 222 is capable of transmitting the operationsignal to the main engine 220. The logic control unit 223 is coupled tothe unloading relay module 222. The logic control unit 223 controls theunloading relay module 222 according to the unloading signal or thereloading signal.

As shown in FIG. 6, which is a schematic diagram of a logic controlmodule according to the present invention, the unloading relay module222 comprises a plurality of relays 2220 and two crimping machines 2221and 2222. One crimping machine 2222 is electrically coupled to theplurality of relays 2220 and the main engine 220, while the othercrimping machine 2221 is electrically coupled to the plurality of relays2220 and the logic control unit 223. The logic control unit 223 furthercomprises a PLC control unit 2230 and a power supply 2231. The PLCcontrol unit 2230 is electrically coupled to the crimping machine 2221in the unloading relay module 222 and the control unit 21 to transmitthe main engine status via network communication.

Please refer to Table 1, Table 2 and Table 3. Table 1 shows a comparisonof consumed power in kilowatt-hours. Table 2 shows comparison of fines.Table 3 shows saved electricity fees (Compared to the year of 2004). Itis observed that the method of the present invention does not onlyreduce the consumed power but also make electricity fees less. On theother hand, the unload/reload determination mechanism of the presentinvention further reduces the fine. For example, according to Table 1 toTable 3, for Industrial Technology Research institute (ITRI), theconsumed power and the fine in 2007 are much lower than those in 2004.Therefore, the method of the present invention helps IndustrialTechnology Research Institute (ITRI) to save plenty of money, as shownin Table 3.

TABLE 1 Comparison of consumed power in kilowatt-hours Campus Chong HsinCampus Kwang-Fu Campus Total Kilowatt- Compared to Kilowatt- Compared toKilowatt- Compared to Year Hour Year 2004 Hour Year 2004 Hour Year 20042004 105,048,000 0 19,500,000 0 124,548,000 2007 101,395,000 3,653,00018,956,000 544,000 120,351,000 4,197,000

TABLE 2 Comparison of Fines Campus Kwang-Fu Campus Total Chong-HsinCampus Compared Compared Thousand Compared Thousand to Year Thousand toYear Percentage Year NT Dollars to Year NT Dollars 2004 NT Dollars 2004(%) 2004 4,424 0 1,716 0 6,140 0 0 2007 917 −3,507 1,009 −708 1,925−4,215 −68.6

TABLE 3 Saved Electricity Fees (Compared to the year of 2004) CampusKwang-Fu Campus Saved Chong-Hsin Campus Moving Saved Moving Saved FineElectricity Saved Fine Total Electricity Fees (Thousand Fees (ThousandTotal Saved (Thousand NT NT (Thousand NT Fee (Thousand Year Dollars)Dollars) Total NT Dollars) Dollars) Total NT Dollars) 2007 −7671 −3,507−11,178 −1,142 −708 −1,850 −13,029

Accordingly, the present invention discloses a method and a system forpower load management, in which two standard values are determined todetermine the timing for unloading/reloading of electrical devicesaccording to a power consumption status and the relation between the twostandard values so that the power consumption status is controlled tothus reduce power consumption. Therefore, the present invention isnovel, useful and non-obvious.

Although this invention has been disclosed and illustrated withreference to particular embodiments, the principles involved aresusceptible for use in numerous other embodiments that will be apparentto persons skilled in the art. This invention is, therefore, to belimited only as indicated by the scope of the appended claims.

1. A method for power load management, comprising steps of: determining a first standard value and a second standard value; determining a first monitoring value and a second monitoring value according to a power consumption status; determining whether the second monitoring value is larger than the second standard value when the first monitoring value exceeds the first standard value; and starting an unloading procedure if the second monitoring value is larger than the second standard value.
 2. The method for power load management as recited in claim 1, wherein the first monitoring value is a moving average of power consumption per unit time.
 3. The method for power load management as recited in claim 1, wherein the second monitoring value is a moving average of power consumption per unit time.
 4. The method for power load management as recited in claim 1, wherein the unloading procedure further comprises steps of: (a) providing a plurality of electrical devices; (b) unloading one device of the plurality of electrical devices; and (c) monitoring the power consumption status for a specific period of time, and returning to Step (b) if the second monitoring value is larger than the second standard value, or stopping unloading the one device if the second monitoring value is smaller than the second standard value.
 5. The method for power load management as recited in claim 4, wherein Step (a) further comprises a step of determining an unloading order of the plurality of electrical devices and selecting an electrical device that is not to be unloaded for the time being.
 6. The method for power load management as recited in claim 4, further comprising a step of switching some of the plurality of electrical devices into an automatic mode or a local mode.
 7. The method for power load management as recited in claim 4, further comprising a step of performing a reloading procedure.
 8. The method for power load management as recited in claim 7, wherein the reloading procedure further comprises steps of: (a) monitoring the unloaded electrical device; (b) determining the relation between the second standard value and the second monitoring value if the first monitoring value is between the first standard value and the second standard value after the unloading procedure has been performed for a period of time; and (c) reloading the unloaded electrical device if the second monitoring value is smaller than or equal to the second standard value; and (d) repeating from Step (b) to Step (c).
 9. The method for power load management as recited in claim 8, wherein the reloading procedure further comprises a step of performing Step (c) when the unloading time of the unloaded electrical device exceeds a threshold value.
 10. The method for power load management as recited in claim 1, wherein the unloading procedure further comprises steps of: (a) providing a plurality of electrical devices; (b) determining whether all of the plurality of electrical devices have been unloaded; (c) performing a first unloading procedure on one of the electrical devices if not all the plurality of electrical devices have been unloaded, otherwise performing a second unloading procedure on one of the electrical devices if all the plurality of electrical devices have been unloaded; and (d) monitoring the power consumption status for a specific period of time, and returning to Step (c) if the second monitoring value is larger than the second standard value, or stopping unloading the one device if the second monitoring value is smaller than the second standard value.
 11. The method for power load management as recited in claim 10, further comprising a step of switching some of the plurality of electrical devices into an automatic mode or a local mode. 12-21. (canceled) 